The invention consists of a profile formed by the union of four elements; it is validly used in the field of window and door frames.
The technique of connecting aluminium profiles and wood fillets aimed at forming window and door frames has been known for some time now. The metallic profile constitutes the outer part of the frame, while the wood makes its inner part. Thus, the weather resistance and waterproof properties of aluminium and the beauty and thermal insulating properties of wood are all exploited.
Metal can be coupled with wood by means of a bonding resin, which is percolated in the space present between these materials. It is for example known the European Patent filed with no. 91116315.2 and published with no. 0 479 106. In this invention, the profile is formed by metal and wood with the interposition of a bonding resin layer. The wood is divided into a plurality of laths placed tightly one close to the other adjacents held together by at least said bonding resin layer. This last one is divided by detachers. Between the bonding resin layer and the metal, also a layer of dethaching materials is applied in order to allow a longitudinal relative sliding between the bonding resin layer and the metal.
Yet, more recently, the method of coupling these materials by means of an intermediate plastic profile spread. For instance, the International Patent filed with no. PCT/EP92/02105 is well known. In this invention, the plastic profile has wings tending towards the outer part of the frame, and fit with corresponding wings created on the wall heading towards the inner part of the frame of the outer metallic profile. In detail, the fitting takes place between a rib created on the lateral internal wall of each metallic wing and a complementary groove created on the lateral outer wall of the plastic wing.
Other metallic wings can be present between the above mentioned plastic wings with the function of maintaining the latter in pretensioning during coupling. The intermediate plastic profile is equipped, on the opposite side of the one in which the above mentioned wings are positioned, with at least one rib which fits in a corresponding groove created in the wood element on the wall tending towards the external part of the frame.
The International Patent filed with no. PCT/EP94/01273 describes an interconnected profile in which, between the metal profile and the plastic profile, there is an anchorage enabling a sliding movement in a longitudinal and transversal sense between these two profiles. This anchorage is obtained by the union of the external elements of shear joint of the plastic profile and those of the metal profile and between the internal elements of joint of the two profiles constituted by two return flanges of the plastic profile and a corresponding number of flanges of the metal profile. These are equipped with a convex surface or with an angle-bent surface. The return flanges of the plastic profile, used to restore the interconnected elements after a transversal movement, are deformed during the assembling stage so that they press against the flanges of the metal profile.
Even though they do not deny the validity of the above mentioned inventions, it has to be considered the fact that the movements between the intermediate plastic profile and the wood fillet are extremely limited. Yet it is well known that, in case of a thermal shock, since the plastic material and wood have a different dilation, the frame formed in this way can undergo permanent deformations.
The ribs of the plastic profile, in both Patents, are pushed with strength in the grooves of the wood fillet. In order to ease this operation a certain tolerance between these elements is envisaged. Yet, in the minimum space that is therein created, water and air can infiltrate with the consequence of the deterioration of wood, caused by humidity, fungus, mildew etc.
Furthermore, the screws fixing the accessories of movement of each sash are fixed onto the metal profile of the sash itself, directly or after having drilled the plastic profile. The screws therefore constitute as many thermal bridges which transmit heat from the outside towards the inside of the metal profile causing condensation or even the formation of dew.
Aim of the invention is that of creating a several elements profile that, thanks to its building characteristics, does not undergo the above mentioned problems.
These as well as other aims are met by the profile for the production of window and door frames as in object, which is formed by a outer metal profile, a plastic material profile, a bonding resin layer and an inner wood fillet.
The plastic profile is equipped with two wings tending towards the outer part of the frame, which laterally embrace the metal profile and slide on it until they meet two wings made on the lateral walls of the metal profile itself. The end of each wing tending towards the outer part of the frame comprises a support pin which is shaped so it shows a rib tending towards the lateral wall of the metal profile. On each lateral wall of the latter profile, starting from the metal wing, a groove is created, having an edge at its end facing the plastic profile.
The wings of the metal profile are chamfered and thus they press the support pins, forcing their ribs to enter in the grooves of the metal profile. The shear between the tooth of each rib and the edge of the corresponding groove, even granting that the two profiles cannot detach one from the other, enables the longitudinal sliding of a profile as compared to the other.
The metal profile of each sash shows the wall facing the inner part of the frame moulded in such a way that, after the coupling of the metal profile with the plastic profile, between the two profiles a chamber is formed. Its extension is sufficient to handle the screws fixing the accessories of movement of the sash itself.
On the wall facing the wood fillet, the plastic profile furthermore comprises at least two wings tending towards the wood fillet itself. At least one of these wings or an arm extending from one of these wings is positioned on a base edge on the side of connection with the wood fillet to carry out the double function of constant fixed spacer of the wood fillet from the plastic profile and of acting as a containing part of the bonding resin percolated.
At least two wings of the wall of the plastic profile facing the wood fillet have the ends hook-bent so that between them and the named wall of the plastic profile some channels, facing each other, are formed.
In the sash, at least one of said wings of the plastic profile facing the wood fillet is extended with an arm having the function of hooking the wood fillet. In the jamb, at least one of said wings of the plastic profile facing the wood fillet is extended with an arm having the function of embracing its lateral outer wall, partially protecting it against weather. This last arm houses in an adequate groove created in the wood fillet itself.
On the wood fillet wall facing the outer part of the frame some slots are created, preferably moulded in dovetail profile.
In the dead bottom channel existing between the plastic profile, the wood fillet and the wing or arm acting as containing part the resin is injected. The resin fixes on the wood fillet. The above mentioned slots created on the wood fillet enable the resin to increase the support surface and therefore to increase the cohesion of the resin itself with wood. The resin also covers the surface of the plastic profile facing the wood fillet but it does not fix on the plastic profile. The hook-shaped wings of the plastic profile, though, act as retainers that avoid the resin to detach from the plastic profile, only enabling it to longitudinally slide with respect to it.
The so formed profile therefore enables a double longitudinal inner sliding: between the resin and the plastic profile and between the latter and the metal profile. This enables the maximum balance to thermal dilations.
The resin completely fills the slots of the wood fillet and melts with it thus strengthening the structure of the frame. The outer wall of the wood fillet is this way protected from water and air.
The screws fixing the accessories of movement of each sash are fixed to the plastic profile and are housed in the channel existing between the latter and the metal profile. Therefore the screws no longer constitute sources of conduction of the external temperature towards the inside of the metal profile.
The metal is completely isolated from the wood because between the two profiles constituted by these two materials the plastic profile and the resin are interposed. There is no contact between metal and wood.
The shear between the wings of the plastic profile and the grooves of the metal profile, thanks to the shape of the parts in contact, is extremely safe and avoid the possible detachment of the parts even though the pressure of the metal chamfered metal wings reduces (because of their flexibility) on the hooking pins.